RF/microwave engineers know well the value of a vector network analyzer (VNA) on the test bench. With such instruments, one can determine the RF characteristics of either active or passive devices. It’s critical to understand the magnitude and phase characteristics of the cables, filters, attenuators, amplifiers, and converters that comprise the signal chain of a given system.
VNAs are, however, a significant investment that must be “future-proofed” to protect such an investment for any possible contingencies down the road. A 2-port VNA capable of measurements out to a given frequency range may suffice today, but next year you may find yourself wishing for greater capabilities in the form of more ports and/or higher frequencies.
That’s where something like Anritsu’s VectorStar VNAs can fit the bill. Starting with the company’s MS4604B 70-GHz mainframe VNA, users can add a 2-port test set to bring the port count to four. The test sets drive small, precise mmWave modules that make true differential measurements from 70 kHz to 220 GHz in a single sweep.
Thus, users can begin with the base mainframe VNA and its 70-GHz bandwidth. Later, if or when their test requirements change, they can upgrade the mmWave modules from 70 GHz to 110, 125, 145, or 220 GHz to account for rising frequencies. And, again, as requirements dictate, they can add a 2-port test set to go from two to four ports for differential measurements.
220-GHz VNA Measurements on Wafers
When it comes to the 220-GHz realm, most VectorStar users are making D-band and G-band measurements on wafer, according to Navneet Kataria, product marketing manager for Anritsu’s benchtop instruments. That’s thanks to the mmWave modules’ 0.6-mm coaxial interface. Users can attach wafer-level probes to the module, such as the single-ended probe with a GSG tip configuration seen in the accompanying video. These probes, available from MPI Corp., come in a variety of pitches, including 50, 75, and 100 µm.
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